The improvements pertain to multiple station, multiple clamp assembly rotary blow molding machines for the manufacture of bottles and the like. In particular, the improvements pertain to eliminating reversal or retraction of rotary actuators at the mold closing the mold opening stations and provision of a mechanically driven and timed unloader mechanism at the mold opening stations. The improvements comprise further improvements to a multiple station, multiple clamp assembly rotary blow molding machine described in applicant's pending U.S. patent application Ser. No. 642,998 filed Aug. 21, 1984. The improvements, however, are not limited to such a machine.
Multiple station blow molding machines of circular or rotary configuration comprise machines with a plurality of stations located about a circular path. Such a machine includes a plurality of clamp assemblies, each containing a mold for one or more bottles. The total number of clamp assemblies equals the total number of stations. The clamp assemblies rotatably index from station to station about the circular path with various operations taking place either at the various stations which are of fixed location or during movement between stations.
In a typical machine each clamp assembly requires a mechanism for closing and opening the clamp assembly to thereby close and open the mold therein and means to assure that the mold remains tightly clamped together during the blowing and prefinishing stages of making the bottle. In applicant's above noted machine, a multiple toggle mechanism actuated by a rotary actuator at the mold close station and a second rotary actuator at the mold open station provides the mechanism. Means are provided on each clamp assembly to engage the rotary actuators at the mold close and mold open stations and to prevent movement of the toggles otherwise than by the rotary actuators. During indexing movement, however, the rotary actuators must reverse and retract in the time between disengagement with the receding clamp assembly and engagement with the approaching clamp assembly. Time and motion are thus wasted in the operation of the machine.
Unloader mechanisms at the mold open station typically comprise a grasping means at the end of an arm that reaches into the clamp assembly from the top or side. Such arms are usually actuated by one or more pneumatic or hydraulic cylinders in response to timing switches or valves on the machine in turn actuated by movement of other portions of the machine. Such pneumatic or hydraulic unloaders are subject to timing difficulties during set-up of the machine and with changes in molds. With the above difficulties in mind, the following improvements have been created.